Use of light emitting diodes (LEDs) as light sources for display devices, illumination devices, and the like is discussed because LEDs consume less electricity and generate less heat. However, LEDs have high directionality, and thus require ingenuity in order to attain uniform light distribution over a wide area.
For example, Patent Document 1 discloses that a light guide body is included that has a light-incident-end face on which light emitted from a light source is incident and a light emission surface for emitting light to be guided, and the light guide body is provided with a local lens array formed in a direction different from the direction of light with a peak intensity in a brightness distribution at an incident position of the light with the highest intensity of light incident on the light-incident-end face. Thus, the inconsistency in brightness is avoided.
Also, Patent Document 2 discloses that a lamp housing having an opening on one end and having a light source accommodation portion whose inner wall is a light reflection surface; a light emitting diode provided in the light source accommodation portion; and a display plate provided in front of the opening are included. Thus, through diffusing and reflecting, light from the light emitting diode is uniformized.
Also, Patent Document 3 discloses that reflection is repeated between light reflected from a micro reflection section in a diffusion layer formed on a reflection surface of light and a reflector provided in the vicinity of a light emitting diode (LED), thereby uniformized light is obtained.
Also, Patent Document 4 discloses that directional light emitted from an LED (especially intensive light directly above the LED) is reflected in the direction of the LED by using a reflection section formed on a radiation surface. Thus, the direction of the light is changed, and the intensity of the light from the LED is reduced in order to obtain uniformized light.    Patent Document 1: Japanese Patent Application Publication No. 2002-343124    Patent Document 2: Japanese Patent Application Publication No. 2003-186427    Patent Document 3: Japanese Patent Application Publication No. 2005-284283    Patent Document 4: Japanese Patent Application Publication No. 2006-12818